Use Gnome-Shell 3.0 themes with Gnome-Shell 3.2

In order to use 3.0 themes instead of 3.2 theme, you need to add theses few lines at the beginning of gnome-shell.css file in the particular gnome-shell theme folder :

.icon-grid {
    spacing: 36px;
    -shell-grid-item-size: 118px;
}

.contact-grid {
    spacing: 36px;
    -shell-grid-item-size: 272px; /* 2 * -shell-grid-item-size + spacing */
}

.icon-grid .overview-icon {
    icon-size: 96px;
}

You can now use search engine in Activities View without freezes.